Sunday, February 2, 2014

Bright and Cheerful Underglaze!

You will know by now that I am a gloomy old chap who lives in a cold part of the world, and I like to make large bowls with dark brown glazes...  All true enough but, there is another side of me.... I have been doing some colourful experiments with underglaze decoration.

Earthenware Pot 12 3/4 inches high (325mm).
I have tended to avoid using ready made glazes, and glaze stains, especially at stoneware temperatures. I prefer to do things the hard way I guess! Recently I descended from my hermit's cave, threw away my hair shirt, and I bought some underglaze colours, the sort that come in small plastic bottles. They are simple to use, anyone who can squeeze sauce (ketchup) over a hot dog, can do a pattern of some sort directly from the bottle with underglaze. Just shake the bottle well, remove the little cap, and squeeze the bottle gently with the tip in light contact with the pot... and a line, or a blob, will spurt out of the nozzle!

Another way to work is to squirt some underglaze into a saucer and apply it with a brush, or a sponge, or with what ever takes your fancy. You can dilute underglaze with water, and apply it in washes like watercolour. Some people spray diluted underglaze with an airbrush.

Thus far I have run some tests to see if the colours will be capable of firing to 1280 degrees Celsius (the bottles claim 1250+), and I have tried decorating on bisqued porcelain, on dry unfired porcelain, and on dry unfired earthenware that had a white slip over it. I have even tried some over a fired glaze.

Earthenware lidded jar, 13 1/4 inches high (335mm).
I found that working directly with a brush on a bisque fired pot was a bit of a struggle. A bisque fired pot is very absorbent, and a brushed line tends to stop abruptly. I found it helpful to sponge or brush some water onto the pot first before following with a brush full of underglaze. I could see that applying underglaze directly from the bottle, or dabbing it on with a sponge would be very straightforward. The good thing about working on bisque is that there is the possibility of washing the decoration off again if something goes terribly wrong.

Working straight onto dry clay, or onto dry slip was the most creative and fun. The underglaze flows better from the brush on this surface, and it is also possible to scratch back through the underglaze into the pot. I did mess up technically a couple of times when applying underglaze over a slipped earthenware pot. After getting the underglaze too thick, I then got things too wet! When I worked back into some thick underglaze with water to try to smear it thinner, this caused the slip to start to bubble and lift. You have got to try these things though!

Earthenware lidded jar, 14 inches high (355mm).
I have stated that underglaze is simple to use..., well, it is and it isn't. Underglaze is the "ukulele" of the world of ceramic decoration! The ukulele can be a very simple musical instrument (that some musicians despise), or it can be technically challenging, and extremely difficult to do well. Underglaze is similar, amazing things can be done with it, and a search online for images of underglaze decoration will show what can be done by a skilled person.

I would have had great trouble trying to do tidy lines and squiggles that I was really in control of squirting it straight from the bottle; and applying it by brush in a confident manner would require many hours of practice. To start with, I fought the stuff, and tried to make it go where I wanted it to go, but later I started to enjoy working with the blobs, squirts, wiggles and smears that the bottle would make, and I started to like the hesitant, draggy line that the brush would make on the absorbent bisque or dry clay. I could tell the brush to do a circle, but the tip would drag and stutter, and limp round in a squarish shape, or spiral. It was fun!

Detail of the first earthenware pot on this page showing underglaze colours that have been applied directly from the bottle and as washes or as lines with brushes. There is also an area with some scratching back through the underglaze to the white slip below it.
It is early days for me, and I don't plan on painting the Mona Lisa with underglaze this week (maybe next week?)! But it is good to have made a start.

After the underglaze decoration goes onto the pot then, you have guessed it, the glaze is applied. With care, this can sometimes be done straight away, or the pot can be bisque fired and the glaze applied by dipping, pouring, brushing or spraying.

The most obvious glaze to use over underglaze is a nice clear transparent one that shows the decoration that is beneath it. However, I can imagine all sorts of possibilities with coloured glazes, and semi translucent glazes, or no glaze at all on something sculptural in high fired porcelain.

*What brand of underglaze did I use? I used Kiwi underglaze (of course!!).

9 comments:

Armelle Léon said...

Lovely work Peter, one can see you are a painter, it is as joyful as country-pots and finally very 'Bernard Leach's spirit', as the early potters were also farmer. Plus the contemporary colors, really nice !!!

Peter said...

Bonjour Armelle,
Thank you for your kind comment. I like the thought of joyful country pots. It was nice to be painting again in this way!

Melissa Rohrer said...

Well, those are fun!

Pat - Arkansas said...

Wonderful!!! While the technicalities are far beyond my ken, I very much enjoyed the results of your labors. What cheerful, and beautiful, pots!

Linda Starr said...

these are just plain fun

smartcat said...

Nicely done! Being a low-fire person, I say keep on experimenting. Just love what you are doing with color and design. I think low-fire colors are like candy!

Peter said...

Thank you Melissa, Pat, Linda, and Smartcat for your comments, good to hear from you. I certainly enjoyed myself with those pots, good to have fun! The experiments will continue with the full colour range at earthenware, and also at stoneware temperatures where underglaze could be a very interesting way to modify a glaze that goes over the top.

Amy said...

Love the underglaze pots! I use AMACO underglaze and have found that it gets bubbly and runs if one tries to recycle it. I always use a paintbrush to apply mine into the etching I did pre-bisque firing with a graffito tool. I learned the hard way, thinking nothing of it and a whole kiln load of pots were ruined. Many are now flowerbed pots. :( Hope you make more!

Peter said...

Good to hear from you Amy,
I enjoyed the underglaze pots.., it took me back to the days when I was a painter!
Interesting about the problem you had with AMACO underglaze, it is certainly something that I should test for to see if it happens with the ones that I use. Very frustrating for you to lose a kiln load, as I know your bowls must take you quite a long time with the texts that you put on them. "Flowerbed pots", our garden is full of them!!!